diff --git a/joint_teapot/__main__.py b/joint_teapot/__main__.py
index 8b1bfea..e604523 100644
--- a/joint_teapot/__main__.py
+++ b/joint_teapot/__main__.py
@@ -122,8 +122,8 @@ def prepare_assignment_dir(dir_or_zip_file: Path) -> None:
     help="upload assignment grades to canvas from grade file (GRADE.txt by default), "
     + "read the first line as grade, the rest as comments",
 )
-def upload_assignment_grades(dir: Path, assignment_name: str) -> None:
-    tea.pot.canvas.upload_assignment_grades(str(dir), assignment_name)
+def upload_assignment_grades(dir_or_zip_file: Path, assignment_name: str) -> None:
+    tea.pot.canvas.upload_assignment_grades(str(dir_or_zip_file), assignment_name)
 
 
 if __name__ == "__main__":
diff --git a/joint_teapot/workers/canvas.py b/joint_teapot/workers/canvas.py
index 34d8562..4e92156 100644
--- a/joint_teapot/workers/canvas.py
+++ b/joint_teapot/workers/canvas.py
@@ -30,11 +30,11 @@ class Canvas:
                 raise Exception(
                     f"Unable to gather students' {attr}, please contact the Canvas site admin"
                 )
-        logger.debug(f"Canvas students loaded")
+        logger.debug("Canvas students loaded")
         self.assignments = self.course.get_assignments()
-        logger.debug(f"Canvas assignments loaded")
+        logger.debug("Canvas assignments loaded")
         self.groups = self.course.get_groups()
-        logger.debug(f"Canvas groups loaded")
+        logger.debug("Canvas groups loaded")
         self.grade_filename = grade_filename
         logger.debug("Canvas initialized")
 
@@ -42,16 +42,18 @@ class Canvas:
         self, dir_or_zip_file: str, create_grade_file: bool = True
     ) -> None:
         if os.path.isdir(dir_or_zip_file):
-            dir = dir_or_zip_file
+            assignments_dir = dir_or_zip_file
         else:
-            dir = os.path.splitext(dir_or_zip_file)[0]
-            if os.path.exists(dir):
-                logger.error(f"{dir} exists, can not unzip submissions file")
+            assignments_dir = os.path.splitext(dir_or_zip_file)[0]
+            if os.path.exists(assignments_dir):
+                logger.error(
+                    f"{assignments_dir} exists, can not unzip submissions file"
+                )
                 return
-            extract_archive(dir_or_zip_file, outdir=dir, verbosity=-1)
+            extract_archive(dir_or_zip_file, outdir=assignments_dir, verbosity=-1)
         login_ids = {stu.id: stu.login_id for stu in self.students}
         for v in login_ids.values():
-            new_path = os.path.join(dir, v)
+            new_path = os.path.join(assignments_dir, v)
             if not os.path.exists(new_path):
                 os.mkdir(new_path)
             if create_grade_file:
@@ -60,7 +62,7 @@ class Canvas:
                     open(grade_file_path, mode="w")
         late_students = set()
         submitted_ids = set()
-        for path in glob(os.path.join(dir, "*")):
+        for path in glob(os.path.join(assignments_dir, "*")):
             filename = os.path.basename(path)
             if "_" not in filename:
                 continue
@@ -70,7 +72,7 @@ class Canvas:
             else:
                 file_id = int(segments[1])
             login_id = login_ids[file_id]
-            target_dir = os.path.join(dir, login_id)
+            target_dir = os.path.join(assignments_dir, login_id)
             if segments[1] == "late":
                 # TODO: check the delay time of late submission
                 if create_grade_file:
diff --git a/joint_teapot/workers/git.py b/joint_teapot/workers/git.py
index 2ac21c2..a8ee8a0 100644
--- a/joint_teapot/workers/git.py
+++ b/joint_teapot/workers/git.py
@@ -76,7 +76,7 @@ class Git:
         while retry_interval and auto_retry:
             try:
                 repo.git.fetch("--tags", "--all", "-f")
-                repo.git.reset("--hard", f"origin/master")
+                repo.git.reset("--hard", "origin/master")
                 repo.git.clean("-d", "-f", "-x")
                 repo.git.checkout(checkout_dest)
                 retry_interval = 0
diff --git a/joint_teapot/workers/gitea.py b/joint_teapot/workers/gitea.py
index 9e37059..7a5a086 100644
--- a/joint_teapot/workers/gitea.py
+++ b/joint_teapot/workers/gitea.py
@@ -21,11 +21,11 @@ class PermissionEnum(Enum):
 
 
 def default_repo_name_convertor(user: User) -> Optional[str]:
-    id, name = user.sis_login_id, user.name
+    sis_login_id, name = user.sis_login_id, user.name
     eng = re.sub("[\u4e00-\u9fa5]", "", name)
     eng = eng.replace(",", "")
     eng = "".join([word[0].capitalize() + word[1:] for word in eng.split()])
-    return f"{eng}{id}"
+    return f"{eng}{sis_login_id}"
 
 
 def list_all(method: Callable[..., Any], *args: Any, **kwargs: Any) -> Any:
@@ -121,9 +121,7 @@ class Gitea:
             }
             try:
                 try:
-                    repo = self.organization_api.create_org_repo(
-                        self.org_name, body=body
-                    )
+                    self.organization_api.create_org_repo(self.org_name, body=body)
                     logger.info(
                         f"Personal repo {self.org_name}/{repo_name} for {student} created"
                     )